Can someone please explain to me what regrinding is all about? I have DOHC ZC if that helps and aftermarket cams just arent around and I've been reading on regrinds but I still dont understand fully why regrinding can give you more flow? Is it because the lop and duration is slightly advance? Any advice and information is greatly appreciated.

 

The lobe is a bump on a circle. The lifter rides on circle when the valve is closed, and then when it rides on the bump the valve opens.

When the cam is reground, they make the base circle smaller - this change alone increases the distance the lifter has to travel from the circle to the tip of the lobe.
That is where the increase in lift is gained.

The lobe can then be reshaped to change duration.

 

Ok, nicely worded. And is duration the time between the valve is completely opened then closed?

 

I wrote 'lifter' in my last post... meant 'tappet'.
Doesn't change the meaning though.


Duration is how long the cycle of opening and closing lasts.
It can be measured in a couple different ways so different manufactures may advertise different numbers for the same measurement.
If they measure directly on the cam they will take measurement right when the lobe starts and finishes.
Another way takes into account for the valve lash. This is a small gap between the tappet and the cam so the measurement would be different.
So when you are comparing duration between different manufactures, you need to know the 'tappet rise' spec and account for that in the calculation.

 

I getcha, thanks man.....I've read a few things on the enternet but they didn't word it as well as you did.